Macroevolution: Its all around us...

thanks for the reference!Another "poof! here is another species" article i came across recently is given below. Imagine, 200 species of guppy in a single (muddy) lake!Title:The effect of selection on a long wavelength-sensitive (LWS) opsin gene of Lake Victoria cichlid fishes
Author(s):Terai Y, Mayer WE, Klein J, Tichy H, Okada N
Source:PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 99 (24): 15501-15506 NOV 26 2002
Document Type:Article
Language:English
Cited References: 30 Times Cited: 11
Abstract:In East African Lake Victoria >200 endemic species of haplochromine fishes have been described on the basis of morphological and behavioral differences. Yet molecular analysis has failed to reveal any species-specific differences among these fishes in either mitochondrial or nuclear genes. Although the genes could be shown to vary, the variations represent trans-species polymorphisms not yet assorted along species lines. Nevertheless, fixed genetic differences must exist between the species at loci responsible for the adaptive characters distinguishing the various forms from one another. Here we describe variation and fixation at the long wavelength-sensitive (LWS) opsin locus, which is selection-driven, adaptive, and if not species- then at least population-specific. Because color is one of the characters distinguishing species of haplochromine fishes and color perception plays an important part in food acquisition and mate choice, we suggest that the observed variation and fixation at the LWS opsin locus may have been involved in the process that has led to the spectacular species divergence of haplochromine fishes in Lake Victoria.

I've always been a bit confused about the distinction between micro and macro that you (and others) have made.Can you explain what is your procedure for deciding which of the following animals are micro-evolved varieties of a single kind of animal, and which are distinctly different kinds of animal?Or if any other anti-macro person could explain it to me, for that matter!1. Saddleback pig 2. Tamworth pig 3. Duroc pig 4. Pot-bellied pig 5. wild boar 6. White-lipped peccary 7. Collared peccary 8. Chaccoan peccary 9. Celebes wild boar 10. Pygmy hog 11. Javan pig 12. Bearded pig 13. Phillipine warty pig 14. Babirusa (scary pig) 15. red river hog 16. musk deer [edited by mick to add a few more photos - sorry to those who only got the first few]This message has been edited by mick, 05-04-2005 06:20 PMThis message has been edited by mick, 05-04-2005 06:22 PM

EZscience,SORRY!!!I edited my post to add a few more photos, and now the pygmy hippo is gone. But anybody who read EZScience's post will realize that the outgroup is again at the end of the post, and is now the musk deer.Actually the musk deer is a better outgroup; the phylogenetic position of the hippo is sometimes considered controversial.EZScience, sorry once again for removing the hippo! thanks for your comments. I hope at least you will enjoy the new pictures, which have a much greater diversity of pig-like animals.Anyway, let's see if any opponents of macroevolution can come up with a good way of distinguishing between "variation within kinds" and "variation between kinds" for these magnificent creatures.Mickps. you are wrong about the peccariesThis message has been edited by mick, 05-04-2005 06:31 PM

Not only a different genus, but a different family - Tayassuidae. Suidae (pigs and hogs) are monophyletic with Tayassuidae (peccaries) at the base of artiodactyla. This arrangement is very well supported by molecular data.Mick

Hi eclipse, Please could you apply this logic to the pig photos I put up for you a few posts ago?I'm just curious to see which of those animals you consider to be micro-evolved pigs, and which are not pigs because they are too different from the archetypal pig you have in mind.One other thing you want to bear in mind - some different species look very similar to each other. take a look at these butterflies, for example. They are from different genera. Cheers!Mick

I've been thinking about this. There appears to be a certain set of people who believe that microevolution can result in different breeds or cultivars within a single species, but that novel species cannot arise through such mechanisms.There must be examples from human agriculture and animal breeding where we have created cultivars or breeds that are not cross-compatible. In other words, breeds that are reproductively isolated from each other.For example, let's consider dogs. People opposed to macroevolution but happy with microevolution will accept that the existing canine breeds are the result of microevolution, mediated by selection from human breeders. Are there any breeds of dog that are reproductively isolated from each other?Let's imagine trying to mate a chihuahua with an Irish wolfhound. The chihuahua measures 6-9 inches from foot to shoulder. The Irish wolfhound measures 30-35 inches from foot to shoulder.Here are some pictures of them, drawn to scale: Is it physically possible for these two animals to have sex with each other and give birth to viable young? If not, that is evidence that microevolution can result in speciation. Does anybody know if this perverse experiment has been carried out? Does anybody know of reproductive isolation occuring between agrictultural cultivars?mick

I think if you put some irish wolfhounds and some chihuahahs on an island together, the chihuahuas would have mysteriously vanished by the next day. The wolfhounds are very scary dogs. Instead of barking, they make a kind of continuous low hungy wailing sound. And they look permanently hungry.I'm not sure i would put too much emphasis on genetic compatibility when we define species. There are plenty of species within mammalia that can crossbreed, but never do in nature, because they have different mating songs, different mating dances, different sexual coloration or aromas, etc. This behavioural/morphological isolation is quite common in the bats and rodents, for example. Genetic incompatibility is just one isolating mechanism amongst many.

Hi Eclipse,I'm not quite sure what you want here. do you want examples of two insects mating and producing offspring that are "better" than themselves, in terms of their ability to reproduce, survive, or what have you?If that is what you want, I can give you some examples.Best wishes,Mick

Hi quig23,Please could you explain? I've never heard the argument that speciation is proof of "de-evolution". What does this mean? Are you suggesting that novel species are "de-evolving" back into an archetypal form? Or are they "de-evolving" into something else?Thanks for your help,Mick

For those unable to access the Nature paper cited by RAZD, I've uploaded the important figure to a web server. At some point my server may bum out (I think it has a maximum band width per month) but if that happens i'll put it somewhere else.Reference: Whiting et al (2003) Loss and recovery of wings in stick insects. Nature 241: 264-267 The tree was generated from aligned18S and 28S ribosomal RNA, and histone 3 dna. The tree is a maximum likelihood tree. Character states were mapped onto internal nodes of the tree using maximum parsimony.The most parsimonious reconstruction of evolutionary events is that there were three wing losses and four wing gains in this clade. What's interesting is that the character states of the living species are very diverse. The Neohirasea lineage has undergone a loss, a gain, and onother loss of wings since divergence from Oligotoma (which is the outgroup to the tree, and is not a stick insect but a webspinner (Embioptera)).If I wanted to guess at the genetic architecture underlying these transitions, the fact that reversions like this are common suggests to me that the "genes" for being winged are not lost when the winged phenotype is lost. It strikes me that the genetic changes must be in the developmental system. As far as I know, stick insects only have wings in the reproductive stage of their life, so the maintenance of winglessness into adulthood represents an extension of the immature phenotype into the reproductive phase.But is it macroevolution? I suspect that some people here might say that, while the loss or gain of wings is a large phenotypic change, these species are all "still stick insects", and that we are only seeing microevolution here.For those people, it would be interesting to know what they make of the loss of wings that occured at the base of the tree (loss of wings in stick insects relative to web spinners). If wing gain or loss is microevolution when it occurs within the stick insect clade, does the initial loss of wings at the common ancestor of stick insects constitute macroevolution?Mick

I agree with you on that, but I suspect those who aren't convinced by macroevolution would want to see the kind of analysis described for walking sticks carried out for a trait that is directly related to speciation, or a trait that is diagnostic of a major group of animals. Wings on stick insects isn't going to do it, because wingedness is characteristic of all sorts of insects, not unique to stick insects. Any variation involving wingedness is always going to be "variation within a kind".I wonder if there are any papers on the evolution of the hexapod body plan? Now that is a trait that is diagnostic of insects per se, and if its evolution can be explained then we have a clear example of macroevolution in a trait related to speciation of a major group.Other examples we might look for are: evolution of aquatic lifestyle in whales; evolution of eusociality in hymenoptera; the origin of flight in bats; loss of wings in worker ants; origin of desalination ability in mangroves; origin of year-long greenness in pines; origin of the cerebral cortex in crocodiles; etc.These are evolutionary events that are undeniably macroevolutionary transitions. There must be dozens of papers that deal with such issues in a phylogenetic context, similar to that used for wingedness in stick insects. I'll take a look in the databases at some point.Best wishes

very cool! I hadn't seen it. That is the kind of evidence we need, accompanied by knowledge of the phylogenetic position of stoneflies in insects (I think they're pretty primitive).Thanks!

Hi EZscience, Do you mean to ask how we map a character onto a phylogenetic tree in order to infer the existence of historical transitions? If so, I can answer your question.If you really do mean "how do they map the phenotype to a gene", i.e. physical mapping of a trait to a specific chromosomal location, that is not something I can help you with! (It's also not something the athors of the walking stick paper did).Mick

okay, I'll post an overview some time over the next day or so. It's not that complicated, but if I just give a quick answer it will likely seem unconvincing.cheersMick

Hi eclipse, I'd be really grateful if you would consider answering Mick's oink challenge.You keep asserting that there are different types of animals, some micro-level variants of each other, and some completely different "kinds". I am at a loss to understand where this idea comes from.Thanksmick